The MSKCC Proteomics Core Facility is dedicated to providing cutting edge mass spectrometric services that aid in the discovery and characterization of important proteins and facilitate timely progression of high priority research. We are requesting funds for a THERMO LTQ-Orbitrap Velos mass spectrometer that, if awarded, would be housed in a state-of-the-art core facility, operated by expert staff with outstanding track records in collaborative research, and its use supported by the Institute for the usable lifetime of the instrument. The new instrument would be indispensable for identification and relative quantification (using a technique termed SILAC) of minute amounts of hitherto elusive proteins as well as for mapping the post-translational modifications on many of the same proteins, and it would be used in support of at least 8 major and 2 minor NIH-funded research projects. The results of these analyses would greatly increase our understanding of the causes and molecular mechanisms for different types of cancer as well as help in the search for new diagnostic markers. PUBLIC HEALTH RELEVANCE: For the past 20 years, the Proteomics Core Facility of Memorial Sloan-Kettering Cancer Center has provided protein discovery and characterization services to help Center scientists in their quest to better understand the mechanisms of cancer, and to diagnose and cure cancer. We have requested an LTQ-Orbitrap Velos mass spectrometer to enable analysis, by our highly skilled staff in a state-of-the-art facility, of minute amounts of physiologically and clinically important but hitherto elusive proteins. The benefit of the proposed instrumentation for the timely progression of laboratory and clinical research programs should be substantial.